Shell growth mechanism in emulsifier-free emulsion polymerization: Morphological and kinetic studies

1993 ◽  
Vol 30 (4) ◽  
pp. 461-468 ◽  
Author(s):  
Show-An Chen ◽  
Song-Tai Lee ◽  
Shien-Jy Lee
Keyword(s):  
Emulsion Polymerization ◽  
Growth Mechanism ◽  
Shell Growth ◽  
Kinetic Studies

scholarly journals Hydrothermal carbonization of fructose—effect of salts and reactor stirring on the growth and formation of carbon spheres

2021 ◽  
Author(s):  
Dennis Jung ◽  
Gözde Duman ◽  
Michael Zimmermann ◽  
Andrea Kruse ◽  
Jale Yanik
Keyword(s):  
Growth Mechanism ◽  
Formation Rate ◽  
Reaction Times ◽  
Kinetic Studies ◽  
Hydrothermal Carbonization ◽  
Sphere Diameter ◽  
Carbon Spheres ◽  
Reaction Conditions ◽  
Reaction Rate Constants ◽  
State Of Matter

AbstractHydrothermal carbonization (HTC) has become a promising technology for the production of hydrochar and carbon spheres. Several studies indicate a strong dependency of the reaction conditions on the sphere diameter. The usage of additives, such as salts, is one possibility to increase the size of the spheres. However, the growth mechanism which leads to larger particles is not fully understood. In this work, kinetic studies of HTC with fructose were performed with different salts as additives. The growth of the particles (the increase in size) has been compared to the formation rates (increase in yield) of hydrochar by using the reaction rate constants from the kinetic model. The results indicate that the acceleration of the growth rate is independent of the formation rate. It is therefore assumed that coagulation, as a growth mechanism, took place. With longer reaction times, the particles reached a stable particle size, independently from the added salts; therefore, it was assumed that the particles underwent some sort of solidification. The state of matter can therefore be described as an intermediate state between liquid and solid, similar to mesophase pitch. Experiments with a stirrer resulted in squashed particles, which supports the model, that the particles exhibit emulsion-like behavior.

scholarly journals Synthesis and kinetic studies of TiO2/polystyrene composite particles by emulsion polymerization

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhang Jianmin ◽  
Peng Zheng ◽  
Sun Xiuguo ◽  
Wang Caihui ◽  
Gao Jungang
Keyword(s):  
Emulsion Polymerization ◽  
Sodium Dodecyl ◽  
Monomer Concentration ◽  
Kinetic Studies ◽  
Composite Particles ◽  
Polymerization Temperature ◽  
Initiator Concentration ◽  
Potassium Persulphate ◽  
Initial Monomer ◽  
Emulsifier Concentration

AbstractIn the presence of titanium dioxide (TiO2) nanoparticles, emulsion polymerization of styrene with sodium dodecyl sulphate (SDS) as an emulsifier and potassium persulphate as an initiator was investigated in detail. It was shown that SDS concentration influences the morphology of the composite particles in higher degree. Moreover, the effects of operating variables such as emulsifier concentrations, initiator concentration, monomer concentration, and polymerization temperature on the kinetic features were also examined. The kinetic data showed that at conditions studied, the rate of polymerization over interval II was proportional to the 0.68 power of the initial emulsifier concentration, to the 2.2 power of the initial initiator concentration and to the 1.6 power of the initial monomer‟s concentration. The initiator concentration has a dominant effect on the rate of the polymerization. The appropriate conditions for polymerization were obtained when emulsifier concentration of 6.5×10-3 mol·L-1, initiator concentration of 4.4×10-3 mol·L-1, the polymerization temperature of 75 °C and the initial monomer‟s concentration of 0.288 mol·L-1 were used. The polymerization rate obtained is more favorable than that of the conventional emulsion approach. The experimental results can be reasonably ascribed to the nucleation mechanism of “TiO2/SDS” micelles in the emulsion polymerization of styrene.

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